Recently, in order to adapt to cordless electrical and electric apparatuses, non-aqueous batteries, such as lithium batteries (lithium primary batteries) and lithium-ion secondary batteries, have attracted attention as a lightweight power source from which high electromotive force and high energy can be obtained. For example, cylindrical-type lithium secondary batteries and others have been produced in large numbers to be used in cellular phones, laptop computers, and the like, and production volume thereof has been increasing year by year. Furthermore, such non-aqueous batteries have also attracted attention as an energy source for next-generation electric vehicles. There also is increasing demand for higher output achieved by further suppressing electric resistance.
As a currently used separator for non-aqueous batteries, there is a porous film formed from a polyolefin made to have fine pores through drawing. However, since the polymer itself is not swellable with liquid electrolyte, only a separator having high resistance can be obtained therefrom. Such a separator cannot satisfy the demand for higher output.
Thus, Patent Document 1 (JP Laid-open Patent Publication No. H5-226002) discloses a gel electrolyte for lithium secondary batteries using an ether-based polyurethane, LiAF6, and propylene carbonate as principal components.
The above invention can provide a lithium secondary battery that can have an interfacial impedance as high as that of liquid electrolyte, by improving contact between the electrodes and the electrolyte.
Further, Patent Document 2 (JP Laid-open Patent Publication No. 2004-31084) discloses a separator for non-aqueous batteries comprising a polymer resin coating layer having fine pores on one surface of its base material.
This document enables to provide a non-aqueous battery having a good workability and a certain level of ability to swell with liquid electrolyte, as well as being capable of preventing internal shorting following detachment and movement of electrode active materials.